On the estimation of time-delays for image source method

The image source method is based on the study of signals reflected by a sedimentary seabed. It produces an estimation of the geoacoustic parameters of the stratified sediments. The key step of this method is the detection and estimation of the time delays of the signals relected by the interfaces between the sedimentary strata. The Teager-Kaiser (TK) operator is known as a reliable way to extract from the recorded signal the time delays of the reflected signals. Due to its sensitivity to discontinuities and excellent time resolution, this operator is a good tool to detect and estimate the time delays. We investigate whether the TK operator associated with time-frequency approaches (spectrogram, wavelets) could be of interest to the detection of time delays and perform better than the TK operator applied directly on the relected signals. The different methods are presented and compared first on synthetic signals. The results show that the use of wavelet transform improve the quality of the time-delays estimation. The algorithm is finally applied to real signals acquired in an acoustic tank experiment and the estimated parameters are very close to the ground-truth.